What is Windows MME vs. Windows Direct Sound?

Audacity Help Forum Windows
1

The manual says that on “devices” you have a choice between Windows MME and Windows Direct Sound. Thanks, but yes, I can see that by dropping down the menu. What I really want to know is “what is the difference”? For what purposes would I choose one over the other? What are the implications of each choice? What I need is an explanation, not an enumeration. Can anybody explain the difference between choosing one or the other? (If this posting gets a good answer, I would suggest adding it to the manual).

Thanks for any help you can provide!

Tom

2

Normally you would go with whatever your computer selects as the default. The manual recommends:
“On Windows XP or earlier and given a recent computer, DirectSound should produce lower latency.”

There’s not usually much (if any) noticeable difference, but there are differences and they are complicated and the distinction is complicated further by which version of Windows you are using. I see there is also a note to the editors of the manual saying: “I still feel MME is the safer default for older, slower machines. It’s possible to give more detail but I don’t think the Manual is the place because of the complexity.” I’m inclined to agree with that sentiment.

There’s some information about DirectSound here: http://en.wikipedia.org/wiki/Directsound
MME is another, older API for Windows.
In Vista/Windows7, both DirectSound and MME are emulated, so the main advantage that DirectSound had on XP (hardware acceleration) is now lost.